Isolating circuit breaker

ABSTRACT

HIGH TENSION ELECTRIC CIRCUIT BREAKER COMPRISING THE COMBINATION OF INTERRUPTER SWITCH MEANS AND DISCONNECT SWITCH MEANS SO COMBINED AS TO PERFORM THE FUNCTIONS OF A HIGH CAPACITY CIRCUIT BREAKER, AND ALSO TO PERFORM THE USUAL FUNCTIONS OF A DISCONNECTING SWITCH, WHEREBY TO PROVIDE A SINGLE SWITCH OF NOVEL STRUCTURE ATTAINING ALL OF THE FUNCTIONS OF PRIOR ART CIRCUIT BREAKERS, INTERRUPTERS AND DISCONNECT SWITCHES.

April 17, 1973 p. E. WESTON ISOLATING CIRCUIT BREAKER 8 Sheets-Sheet lOriginal Filed Nov. 14, 1968 D. E. wEsToN Re. E27,(:325

ISOLATING CIRCUIT BREAKER 8 Sheets-Sheet 2 April' 17, 1973 OriginalFiled Nov. 14, 196B AJ www RNE mi @A NA NN@ NNW@ NNI@ April 1.7, 1973 DE, wEs'roN Re. 27,625

ISOLATING CIRCUIT BREAKER Original Filed Nov. 14, 1968 Sheets--Sheet 3,@Mfrmm r ww, w\\.oo Naw@ fwn,

i J@ j Sw NWUA www o, W QW April 1 7, 1973 D.E.WEST'ON R,z7,s2s

ISOLATING CIRCUIT BREAKER Original Filed Nov. 14, 1968 8 Sheets-Sheet 4D. E. WESTON I SOLAT ING C IRCUIT BREAKER April l 7, 1973 8 Sheets-Sheet5 Original Filed Nov. 14, 196B f w ,f 4M 2 f M H 5 3 @y x II oa 0 m M jf f II /hl fr 0 .9 M /7 y @lwlllf f @4% .f lm;

April 17, 1973 D. E. wEsToN ISOLATING CIRCUIT BREAKER 8 Sheets-Sheet 6Original Filed Nov. 14, 1968 April 17, 1973 .Y D. E, WESTON Re. 27,625

IsoLATING CIRC'IT BREMEN Original Filed Nov. 14, 1968 8 Sheets-Sheet 7D. E. WESTON I SOLAT ING CIRCUIT BREAKER April 17, 1973 8 Sheets-Sheet 8Original Filed Nov. 14, 1968 United States Patent Oce Re. 27,625Reissued Apr. 17, 1973 27,625 ISOLATING CIRCUIT BREAKER Donald E.Weston, East Sebago, Maine, assignor to H. K. Porter Company, Inc.

Original No. 3,566,055, dated Feb. 23, 1971, Ser. N o. 775,660, Nov. 14,1968. Application for reissue Oct. 29, 1971, Ser. No. 193,836

Int. Cl. H01h 31/00 U.S. Cl. 200-48 SB 30 Claims Matter enclosed inheavy brackets appears in the original patent but forms no part of thisreissue specification; matter printed in italics indicates the additionsmade by reissue.

ABSTRACT F THE DISCLOSURE High tension electric circuit breakercomprising the combination of interrupter switch means and disconnectswitch means so combined as to perform the functions of a high capacitycircuit breaker, and also to perform the usual functions of adisconnecting switch, whereby to provide a single switch of novelstructure attaining al1 of the functions of prior art circuit breakers,interrupters and disconnect switches.

BACKGROUND OF THE INVENTION High tension electrical switchgear hasconventionally consisted of (a) circuit breakers, (b) disconnectswitches and (c) interrupters.

Circuit breakers are high capacity load-carrying devices capable oftransmitting high load currents at high voltages. Their primary functionis to stop the high flow of current when a circuit is to be opened. Theyare [also] specifically capable of stopping the flow of current for anyand al1 circuit conditions, i.e., load', [and] no-load and faultconditions [of the circuit] whenever the circuit is to be opened, andalso for closing the circuit under all circuit conditions.

Disconnect switches are also high capacity load-carry- `ing devices, butthey have no capability for stopping the flow of current. Their primaryfunction when closed is to connect various circuit components together,and when opened to disconnect said components and insert a sufcientlylarge gap in the circuit to prevent inadvertent reclosure of thecircuit.

In a high voltage, high amperage circuit, it is necessary to employ bothcircuit breakers and disconnect switches, the former to open the circuitagainst [large] current flow and the latter to open the circuit against[all ow] inadvertent reclosure, i.e., to electrically and physically[isolate] separate the circuit components.

An interrupter switch generally is not a load-carrying device, but aspecialized instrument inserted momentarily in a circuit for the purposeof stopping ilow of relatively nominal currents.

[In those circuits having nominal current dow, it] It is conventional inelectric circuits to combine an interrupter switch and a disconnectswitch in such fashion that the interrupter is normally out of circuitand the disconnect switch carries all the current. Upon opening,however, the interrupter is momentarily placed in series circuit withthe disconnect until the disconnect has moved sufficiently to preventarc-over, whereupon the interrupter opens to [break] interrupt thecurrent dow and the disconnect continues to full open position.

There are also nterrupters that carry load current and operate to stopthe flow of load current in a circuit, but they remain essentially aspecialty instrument, for specific limited service and are neitheradapted for nor intended to act as a circuit breaker or to perform thebroad spectrum functions of a breaker in a circuit. Com.-

bination disconnect and load-carrying interrupter switches` of thisgeneral character are sometimes called "circuit Switchers, which termiis not to be confused with circuit breaker.

Manifestly, there are those circuits which require all three of thedescribed switch structures, i.e., circuit breakers, interrupters, anddisconnects, to effectively open and/or close the circuit.

In regard to combination disconnects and interruptersl reference is madeparticularly to Gussow et al. 3,154,656 and Lindell 3,268,696, and alsoto Schwager 2,838,637.

As part of the background, special reference is made to British Patent1,028,719 which discloses a combination disconnect and interrupterswitch wherein a plurality of vacuum tube interrupters are mountedwithin an insulated housing and connected in series with one another andcontacts at the ends of the housing, the housing being mounted toconstitute a double-break disconnect switch and being movablesubsequently to opening of the interrupters to completely isolate theinterrupters from the circuit. This switch has marked similarity inappearance, but not in operational performance, to the preferredembodiment of the apparatus of this invention. See also U.S. Patent2,710,322.

DEFINITION OF TERMS The electrical industry apparently does not use theterms above discussed in a specialized word of art sense which is hereintended, but rather, frequently in interchangeable ana/ or overlappingsenses. For example, circuit breakers include interruptng contacts whichins terrupt" the circuit; interrupters are sometimes said to "break orropen a circuit; and disconnect switches are said to ropen a circuit andto isolate a circuit component even though the only function performedis insertion of a single air gap in the circuit.

Lacking other specific terms well known in the electrical art, the aboveand below-defined terms will be used herein in accord with thespecialized or specific definitions given:

The terms break, "breaking and circuit breaking operations refer to thefunctions performed in a circuit by a circuit breaker, as the latterdevice has been above described.

Interrupt," interrupting and interrupter" refer to the deviceconventionally known as an interrupter switch as above described, and tothe specialized or limited functions heretofore performed thereby in acircuit (especially as contrasted to the broad spectrum functions of acircuit breaker).

"Disconnecf and "disconnecting refer to the device conventionally knownas a disconnect switch and to the functions it performs in a circuit, asabove described.

llsolate, as used in connection with the apparatus of the invention, isintended to mean total isolation of certain components of the apparatusfrom` the circuit, i.e., insertion of large air gaps to both sides ofsaid components so that they have no connection whatever with any partof the circuit.

SUMMARY OF THE INVENTION The object of the present invention is toprovide an improved economical switch structure embodying all of thefunctions of the prior switches into a single unitary device.

I call this device an Isolating Circuit Breaker," as it performs thefunctions of both breaking the circuit and isolating the circuit breakermeans from the remainder of the circuit, thereby disconnecting thecircuit. The device inherently embodies and performs the ultimatefunctions of an interrupter, or considered alternatively, does away withthe need for an interrupter.

Moreover, it is an object of the invention to constiute the isolatingcircuit breaker in such manner that vhat previously were simply lowcapacity interrupting levices now become adapted to performance of high:apacity circuit breaking functions.

Specifically, it is the object of the invention to embody n onestructure the combination of disconnect switch neans and interrupterswitch means in such manner that he structure performs the functions ofboth a circuit ireaker and circuit disconnecting means.

,Another object is to embody the isolating circuit Jreaker in suchstructural form as to facilitate its physi- :al removal from theenvironment of the circuit in the pen position thereby to provide forsafe servicing of he operating components thereof.

Additional objects and advantages will become mani- 'est as thedescription proceeds.

THE 'DRAWINGS FIG. l is a perspective view of a three phase high ten-`ion 'isolating circuit breaker provided in accordance with he presentinvention;

FIG. 2 is a cross sectional view taken substantially on ine 2-2 of FIG.l;

FIG. 3 is a schematic representation of a two module solating circuitbreaker;

FIG. -4 is a schematic representation of a double-type solating circuitbreaker comprised of two four-module mits;

FIG. 5 is a horizontal longitudinal section of one-half f the movableblade portion of a four-module isolating :ircuit breaker;

FIG. 6 is an enlarged elevational view of the circuit nreaker operatingmeans of the apparatus shown in IG. 5;

FIG. 7 is a detail view taken substantially on line '-7 of FIG. 6;

FIG. 8 is a plan view of the operating mechanism for he isolatingcircuit breaker, showing the same in switch :losed position;

FIG. 9 is a view similar to FIG. 8 but showing the perating mechanism inan intermediate switch openng position in solid lines and in full openposition in lotted lines;

FIG. 10 is a vertical section taken substantially on line l0-10 of FIG.8;

FIG. 11 is a plan view similar to FIG. 8 showing a modified form ofoperating mechanism; and

FIG. 12 is a graphic illustration of the mode in which interrupters areadapted to performance of circuit ireaking functions pursuant to thisinvention.

DESCRIPTION In order to acquaint those skilled in the art with thenanner of making and using my invention, I have shown rnd will nowdescribe what I presently contemplate to e the best mode of carrying outmy invention.

In its preferred embodiment, the complete switch tructure comprises astationary frame 20 including Lpaced parallel frame parts 20a and 20h,and a movable 'rame 21 mounted on and guided by the stationary frame.l`he stationary frame parts 20a and 20h mount respecive ones of one ormore pairs of stationary disconnect :ontacts 22, each of which ismounted on an insulator stack 23 and adapted to be connected with therespective :art of a transmission line 24. In FIGS. A1 and 2, I have:hown a switch structure for a three phase high voltageligh currentpower transmission system comprising three ines 24a, 24h, 24e, and havethus provided and shown hree pairs of said stationary contacts 22 andtheir sup- )orting insulators 23; adjacent contacts being spacedransversely from one another and vertically above the "rame at the phasespacings required for the system.

The movable frame 21 is in the form essentially of 1n H and has theopposite ends of its two end legs slidably guided in vertical channels25 secured to the stationary frame, whereby the H frame 21 may be raisedand lowered relative to the stationary frame. The means for raising andlowering the frame 21 may take any of a variety of forms, for example, apair of hydraulic or pneumatic cylinders 26 secured respectively to theframe parts 20a and 20h and each equipped with a movable piston 27connected to a pair of cables 28 which in turn are connected to the Hframe so as to raise and accommodate gravity lowering of the frame asthe pistons are moved in opposite directions in the cylinders.Preferably, the pistons`v are synchronized for conjoint operation tomaintain the frame 21 level.

Mounted on the cross beam of the H frame 21 are one or more T-shapedmovable switch components 30, each of which is mated to a respectivepair of the stationary contacts 22. In a three phase system, there arethree components 30 as shown. The vertical leg of the T of eachcomponent comprises essentially a mounting insulator, somewhatcomparable to the insulators 23, and the horizontal leg thereofcomprises a combination circuit breaker and double break disconnectswitch as will presently be described.

In the structure shown, each of the components 30 is mounted on theframe 21 for rotary movement through an arc, preferably not less than 60and not more than 120, so that the horizontal leg thereof can be rotatedcounterclockwise to a switch open position as shown in FIG. 1, whereinthe leg is disposed transversely of the respective transmission line 24and in spaced relation to both of the respective stationary contacts 22,and can be rotated clockwise to a switch closed position wherein thehorizontal leg of the T extends between the respective pair ofstationary contacts and makes electrical contact therewith. For thelatter purpose, each end of the horizontal leg is equipped with a iiatblade contact 32 and each of the stationary contacts 22 is generallyC-shaped to receive the blade as it is rotated theretoward. The C-shapeo-f the stationary contacts aords the advantages of shielding the bladecontacts 4and mitigating such formatiion of ice on the contacts as wouldimpair switch operation in outdoor installations in cold climates.

Essentially, as is illustrated schematically in FIG. 3, the horizontalleg of each switch component 30 comprises a central section 33 coupledto the vertical leg 31 of the T and containing circuit breaker operatingmeans, a pair of insulated housings 34 extending to opposite sides ofsaid central section, circuit breaking means 35 in each of saidhousings, means 36 electrically connecting the adjacent ends of thecircuit breaking means together, and means 27 connecting the remote endsof the circuit breaking means to the respective ones of said blade-likecontacts 32. Thus, in switch closed position (as shown in FIG. 3) thecircuit is made through two pairs of disconnect contacts 22-32 and t-woof the circuit breaking means 35, all connected in series. In switchopen position (as will be described) there are four gaps in the circuit,i.e., at each of the circuit breaking means 35 and at each of the twopairs of disconnect contacts 22-32; the latter two gaps (as shown inFIG. l) constituting disconneet switch gaps and totally isolating thecircuit breaklng means from the remainder of the circuit.

In a second embodiment, each half of the horizontal leg of the Tcomponent 30 is comprised of two of the insulated housings 34, eachcontaining a circuit breaking means 35 (see FIG. 4 as exemplary) wherebythe circuit is made through four circuit breaking means and the twopairs of disconnect contacts, all in series circuit.

For extremely high voltage systems, T components 30 may be compounded ineach phase, as illustrated in FIG. 4, to facilitate attainment of highvoltage circuit breaking capabilities by series circuit application of aplurality of relatively low voltage interrupting devices. Specically,two or more T components 30 may be mounted at appropriate spacings tomake Contact with one another and to separate from one another uponrotation in the same directions. Thus, with a single component as shownin FIG. 3 or with two components as shown in FIG. 4, 2, 4, 6 or 8circuit breaking means 35 may be provided in series circuit.

For purposes of particular description herein, I have selected thatembodiment wherein the Switch structure comprises a single T component30 provided with a horizontal leg housing four circuit breaking means,as will now be described in conjunction with FIGS. to ll.

As briefly set forth above, the horizontal leg of the T componentcomprises a central section33 connected rigidly to the upright insulator31, and a pair of leg portions each of which comprises a pair of hollowinsulators 34, an intermediate housing segment 38 and an end cap 39mounting the respective disconnect contact 32.

Each hollow insulator 34 houses therein an interrupting device 40 and abypass or shunt switch device 44, which together comprise the circuitbreaking means 3S above referred to. The interrupting devices 40 arepreferably vacuum tube interrupters conventionally available on themarket and well known to those skilled in the art. Consequently, theywill not be described in detail herein except to note that eachcomprises a tube of insulating material evacuated to a iinite degree andcontaining a pair of separable contacts, one of which is movable andadapted to be actuated by means of a rod 41 projecting from one end ofthe tube. Adjacent ones of the interrupters 40 are mounted with theiractuator rods 41 juxtaposed and conductive means is provided between therods to electrically connect the movable contacts. The other contact ofthe outboard one of the interrupters is connected by means 37, such as abraid conductor or the like, to the adjacent disconnect contact 32; andthe other contact of the inboard interrupter is similarly connected by abraid or like means 36 to its counterpart in the other half of thehorizontal leg of the T. The interrupters are thus mounted back-to-backto minimize problems consequent upon polarity sensitivity and/orelectrical nonsymmetry of the vacuum tube devices.

The bypass or shunt switches 44 each comprise a loadcarrying conductiverod or bar 45 and a plural linger movable contact 46 engageable with anddisengageable from the bar. As with the interrupters, the movablecontacts of adjacent shunt switches are disposed adjacent one anotherand electrically connected. The outboard shunt bar 45 is connected bybraid or like means 37a to the disconnect contact 32, and the inboardbar 45 is connected by a braid or like means 36a to its counterpart onthe other side of the center section 33.

For purposes of actuating the switches 40 and 44 in predeterminedsequence` the intermediate housing segment 38 mounts an operatingmechanism 50, such as a cam, toggle link or like mechanism, adapted tobe driven from an insulated rotary shaft 51 that extends upwardlvthrough the upright insulator 31 into the center section 33. Within thesection 33, the shaft 51 carries a pair of crank arms 52 which areconnected respectively to a pair of operating links 53 that extend inopposite directions from the center section to the respective mechanism50.

As shown in FIG. 6, each mechanism 50 of the illustrated embodiment ofthe switch comprises a toggle-link apparatus including a bellcrank lever54 pivotally mounted on a pin 55 secured to the housing segment 38 andpivotally connected at its opposite ends to the link 53 and a verticallyreciprocable operator 56 to drive the latter upon movement of the link53. The operator is guided for vertical movement by three pins or studs57 which are secured to the housing segment 38 and extend throughvertical slots 58 in said operator plate.

Pivotally connected to the operator are the inner ends of a pair ofbellcrank levers 59 which extend downwardly from the operator torespective ones of the movable shunt contacts 46, the levers each beingpivotally mounted on a pin 60 secured to the housing segment 38.

As shown in FIGS. 6 and 7, each contact 46 comprises two sets of spacedparallel contact lingers 61 disposed to opposite sides of the respectiveload-carrying bar 45, each finger being in the form of a bellcrank andthe tingers of each set being pivotally mounted on a common pivot bolt62 which is mounted on the segment 3.8. At their ends opposite the bar,the fingers of each set receive a pin 63 to which a respective one of apair of toggle links 64 is pivotally connected. The two toggle links inturn are pivotally connected to one another and an operating stud 65positioned on the center line of the shunt switch, each such stud 65being pivotally connected to the lower end of the respective one of thecranks 59'.

By virtue of the described structure, as the shaft 51 is rotated in theclockwise direction as viewed in FIG. 5, the link 53 is moved toward theouter end of the leg of the switch, the bellcrank 54 is swung clockwise,the operator 56 is raised upwardly, the levers 59 are moved toward oneanother, the toggle links y64 are collapsed toward one another, and thesets of contact fingers are moved away from one another and the bar 45to shunt switch open position as shown in dotted lines in FIG. 7.

Upon reverse operation, the sets of contact lingers are, of course,closed upon the bar 45 in obvious manner. However, upon closingmovement, it is desirable to establish a wiping engagement between thelingers and the bar to insure good contact, and I provide for this by soproportioning the toggle links 64 that as they move through theiron-center position they physically llex the contact lingers and therebycause the same to have momentary high pressure sliding engagement withthe bar 45. Then, 1 move the toggle slightly overcenter to permitsprings 66 or the like (disposed between the stud 65 and each of thepins 63) to maintain a predetermined compressive force on the contacts.Also, movement of the toggle overcenter serves to lock the contactsagainst inadvertent opening in the event of surge currents or otherforces emanating from electrical phenomena to which the switch isexposed. To accommodate the described functions, each link 64 has aslight lost motion connection with its respective pin 63.

To insure good current transfer, the contact lingers 61 are assembled onthe pivot bolts 62 with interposed silver washers and Bellville springwashers, as illustrated in FIG. 6, whereby to constitute the bolts 62and the housing segment 38 a conductive link between the shunt switchcontacts.

Adjacent the upper end of the operator plate 56, a pair of toggle links67, in the form suitably of bellcranks, are pivotally mounted on theplate guiding studs or pins 57. At their upper ends, these links arepivotally connected to operating studs 68 for the interrupters 40 andconstitute a conductive link between the interrupter contacts. At theirlower ends, they carry pins 69 which are received in vertical slots 70in the operator 56, the two pins being interconnected by a tensionspring 71. The slots 70, which are shorter than the operator guide slots58, are so proportioned that the pins 69 are not engaged by the operatorin the switch opening direction until after suliicient movement hasoccurred to result in substantially complete opening of the shunt switchcontacts 46 in the manner above-described.

As known to those skilled in the art, the vacuum tube interrupters 40have an extremely short stroke of contact movement, whereby the togglelinks 67 require only a slight movement. To obtain the required stroke,I mount the toggle links to have equal but small arcs of movement to theopposite sides of the on-center position thereof. Consequently, as theshunt contacts approach their full open positions, the plate 56 engagesthe pins 69 and moves them upwardly to slightly beyond their on-centerposition, whereupon the spring 71 drives the links rapidly to theiropposite or upper overcenter position (such movement being accommodatedby the slots 70 which by now are positioned primarily upwardly above thepins 69).

During the initial upward movement of the pins 69 to substantially theiron-center position, the links 67 are operated to move the interrupteroperating studs 68 a short distance toward one another. To accommodatethis movement without disturbing the interrupter contacts, each stud 68has a lost motion connection with the operating rod 41 of the respectiveinterrupter. Specifically, each stud 68 comprises a tube slidablymounted on the respective rod and having an inwardly directed ange 72 atits end that is opposed to and has lost motion relative to an outwardlydirected flange 73 on the rod l41, whereby the initial movement of thelinks 67 results solely in bringing the flange 72 adjacent or into bareengagement with the flange 73 without moving the rod 41. Then, when thespring 71 starts to drive the links 67, the ange 72 engages the fiange73 whereby the spring 71 drives the interrupters to open position athigh speed. For purposes of maintaining pressure on the interruptercontacts in closed position and facilitating closing operation of theinterrupters, a compression spring 74 is preferably disposed between thestud 68 and the rod ange 73.

Thus, as the shaft 51 is rotated in switch opening direction, the shuntcontacts 46 are forced open fully, and thereafter the interrupters areoperated to open position at high speed.

Upon reverse rotation of the shaft 51 from switch open position, thelink .or rod 53 pulls the bellcrank lever 54 back toward the positionshown in FIG. 6. As this occurs, the slots 70 (which now extend upwardlyabove the pins 69) prevent actuation of the pins 69 and links 67 untilthe shunt switch contacts 46 are fully closed, and thereafter the links67 are actuated to result in high speed reclosing movement of theinterrupters 40.

For purposes of driving the switch to effect operation of theinterrupters and the shunt switches, and also to effect opening andclosing movement of the disconnect switch means provided by the contactpairs .2'2-32, the mechanism shown in either FIGS. `8 to 10 or FIG. 11is provided for rotating both the shaft 5,1 and the insulator 31 intimed relationship. In a three phase assembly of three of the switches,as is shown in FIGS. 1 and 2, operating mechanisms may be provided forall three switches, all driven off a common prime mover shaft.Alternatively, only one operating mechanism need be provided, the samebeing connected for example to the central one of the three switches andthe other two or outboard switches being operated by slave connectionsto the center switch.

Operation may be effected manually from the ground, or by means of apower operator such as an electric or hydraulic motor which may bemounted either on the ground or on the movable frame 21 of the threephase switch assembly'ln FIG. 1, I have shown a power operator 80mounted at substantially ground level and connected to the center one ofthe switches 30 by a telescopic rotary drive shaft 81 operating througha gear box 82. Referring to FIG. 10, the gear box includes ahorizontally disposed rotary drive shaft 83 which extends adjacent theinsulator BA1 of the center switch and is there provided with an inputbevel gear 84.

The insulator 31 is tubular and the insulated shaft 51 extends axiallytherethrough, whereby to provide a pair of coaxial control devices whilemaintaining an insulating gap between the live switch components and thegrounded supporting steel. The insulator 31 is mounted on a boxlikesupport 485 and this support is journalled by bearings B6 on the main orcross beam of the movable H frame Z1. The shaft 51 extends downwardlythrough the box support 85 and the frame 21 and is rotatably supportedadjacent its lower end by bearings 87 on the frame 21. The box 85provides a housing for switch operating mechanism, and the downwardextension of the shaft 51 facilitates provision of slave connections tothe other two switches. as will presently appear.

The input bevel gear 84 is meshed with a complementary gear VI8'8 forrotating a vertically disposed shaft 89 which is -journalled in theframe 21 and extends upwardly through an arcuate slot in the base wallof the box 85, the slot being of sufficient arcuate extent toaccommodate predetermined rotation of the insulator 31, for example, 90degrees rotation. Within the box, the shaft 89 carries an interruptedspur gear 91 having an eccentric pin 92 projecting from its uppersurface. The gear teeth on the member 91 are intended to mesh with a`ring gear segment 93 on the inner surface of the box 85, but at thebeginning of the cycle said gear teeth are interrupted so that initiallyonly the member 91 will rotate.

As the member 91 is rotated in a counterclockwise direction as shown inFIG. 8, the pin 92 will first engage the mid-portion of the right leg ofa Y-shaped lever 94 pivoted at 95 in the box 8'5 and move the sametoward the center of the box. A link 96 interconnects the free end ofthe lever 94 and a crank 97 affixed to the shaft 51, whereby the shaft51 is rotated in a clockwise direction to operate the shunt contacts 46and the vacuum tube contact rods 41 in the manner above-described. Thisfunction occurs in an extremely short period of time inasmuch as thegear 91 is required to rotate only about 30 degrees total and itsmovement is amplified by the link 94 to drive the shaft 511 to theextent required to operate the shunt and vacuum switches.

While the shaft 51 is being rotated, a second link 98 coupled to thecrank 97 consumes a predetermined lost motion relative to a lever 99 sothat as the shaft 51 approaches the limit of its clockwise movement saidlever is actuated quite rapidly to drive a lock bolt 100 out of lockingengagement with a stop 101 on the frame 21 and into locking engagementwith a keeper 102 mounted on the shaft '51 (which at this timehasrotated into alignment with the bolt).

The bolt 100 when engaged with the stop 101 se-rves to lock thedisconnect switch in closed circuit position as protection against surgecurrents and the like. It also insures that only the shaft 51 rotatesduring in-itial opening operation of the gear 91, i.e., during the heavyload part of the cycle of operation of the toggle mechanisms 50. Then,the lock bolt is f-reed from the frame to accommodate the next sequencein the operation--opening of the disconnects-and substantiallysimultaneously locks the shaft 51 to the insulator 31 for conjointrotation with the latter so as to maintain the status quo (open circuitcondition) of the circuit breaking means.

As the bolt 100 engages in the keeper 102, the teeth on the interruptedgear 91 engage with the teeth on the gear segment 93 and initiaterotation of the stack 31 (together with the shaft `51) in thecounterclockwise direction, thereby to swing the movable disconnectcontacts 32 out of engagement and away from the stationary disconnectcontacts 22, whereupon the operating mechanism assumes the positionshown in dotted lines in FIG. 9. Preferably, the T component 30 isIrotated 90 degrees as shown in FIGS. 1 and 2 so as to dispose thehorizontal leg thereof perpendicular to the plane of the respectivetransmission line 24 and open up a pair of large air gaps in the line.Due to the [double break] two air gaps or .s0-called double breakdisconnection thereby achieved, the vacuumA tube interrupters 40 aretotally isolated from the circuit.

l In a three phase installation, as previously noted, each of the threeswitches may embody the operating mechanism of FIGS. 8 to l0, each beingdriven by a gear 84 from a common drive shaft, and this generally wouldbe preferred. However, slave drives can be utilized, the same extendingfrom the center switch to the outboard switches and comprising crankarms and links 103 connected to the extended lower ends of the shafts51. In this case, the slave units would not require all of the mechanismof FIGS. 8 to l0, but each would require only 9 the link 98, lever 99,lock bolt 100 and keepers 101 and 102.

The ultimate open position of the switch (switches), may be determinedby predetermined operation of the drive mechanism, disengagement of theteeth on member 91 from the teeth on gear segment 93, engagement of themargin of the slot 90 with the shaft 89, or a position stop on the frame21 associated with a suitable part of the stack 31, box 85 or shaft 51.

To close the switch, the drive means is operated in the reversedirection to rotate the gear 91 clockwise as viewed in FIG. 9. Thisresults, first, in rotating the gear 93 and stack 31 to close thedisconnect switch contacts and to return the operating means to theposition shown in solid lines in FIG. 9, whereupon the gear 91disengages from the gear teeth 93.

At this time, the pin 92 engages the lefthand leg of the Y-shaped lever94 and forces the left leg thereof to the left, whereupon the links 96and 98 and lever 99 are operated to release the lock bolt 100 from theshaft 51. The bolt 100 is moved by its associated spring to release theshaft 51 from the box 85 and ultimately to lock the box to the framemounted keeper 101. As the bolt clears the shaft keeper 102, the shaft51 is rotated counterclockwise to operate the toggle link mechanisms 50in the closing direction, whereby to close the shunt contacts to remakethe electrical circuit, and thereafter to close the vacuum tube contactsto return the switch to its original closed circuit condition.

An alternate form of switch operating mechanism affording the advantageof very high speed opening operation of the circuit breaking means ofthe switch is shown in F'IG. 1l. In this embodiment a gear 91a similarto the gear 91 is mounted and driven in the same manner as the latter,the gear having interrupted peripheral teeth adapted to engage with theteeth on a gear segment 93a secured to the interior of the box 85. Onits lower surface, the gear 91a is provided with a pair of cam tracks104 and 105 adapted to receive follower pins mounted on respective onesof a pair of levers 106 `and 107 which are connected to and operate apair of lock bolts 108 and 109 associated respectively with a framemounted keeper 101a and a keeper 102a associated with the shaft 51, thetwo bolts performing the same functions as the bolt 100 of FIGS. 8 to10.

The peripheral teeth of the gear 91a mesh with interrupted peripheralteeth on an intermediary gear 110 which is adapted to be rotated duringthe initial arc of rotation of the gear 91a, i.e., before but not duringrotation of the box 85 and stack 31. The gear 110, which is journalledon the bottom wall of box 85, is provided with a crank arm 111 connectedto a quick trip toggle linkage 112, which in turn is connected to acrank arm 113 on the shaft 51. The linkage 112 is comprised of a pair oftoggle links 114 and 115 pivotally connected respectively to the cranks111 and 113, a trip link 116 connected to the common pivot 117 of thelinks 114 and 115, and a trip pin 118 fixed to the base of box 85 andprojecting upwardly to the level of the trip link 116, which is thebottommost of the three links.

Also associated with the crank arm 113 on shaft 51, and thus with thelinkage 112, is a circuit breaker operating spring 119, which ispreferably a heavy duty compression spring housed in a casing 120mounted on the box 85 and connected to the crank 113 by a piston and rodassembly 121.

In use, as the gear 91a is rotated in switch opening direction, the gear110 is initially rotated to swing the crank arm 111 in a clockwisedirection. As such movement occurs, the trip link 116 is engaged withthe trip pin 118 and thereby requires the toggle links 114 and 115 tobuckle overcenter under the pull imparted thereto by crank 111. As soonas the toggle buckles, the previously stored energy in spring 119immediately takes over and drives the piston and rod 121 outwardlythereby co1- 10 lapsing the linkage 112 and rapidly driving the crank113 and shaft 51 in the clockwise direction necessary to operation ofthe vacuum and shunt contacts, whereby these contacts are driven open athigh speed to assure performance of the circuit breaking function.

Continued rotation of the gear 91a then results in looking the shaft 51to the box 85 and stack 31 by operation of the bolt 109, straighteningout of the linkage 112 by continued rotation of the gear 110, release ofthe box from the frame by operation of the bolt 108, and finallyrotation of the stack to full open position.

In the latter phase of its ope'ration, the mechanism of FIG. 11 providesfor fail-safe operation of the circuit breaking contacts by themechanical linkage between the cranks 111 and 113; i.e., if the spring119 did not drive the crank 113 or did not drive it far enough, thecrank 111 and linkage 112 will positively pull the crank 113 and shaft51 into full switch open position.

Upon closing of the switch, the sequence is reversed essentially asdescribed in connection with FIGS. 8 to l0, except that as thedisconnect switch is closed the gear is driven to cause the linkage 112to operate the crank 113 to close yfirst the shunt contacts and then thevacuum contacts, and in so doing again loads the spring 119 to prepareit for the next switch opening operation; the trip link 116 ultimatelyengaging over the pin 118 to lock the spring in energy stored condition.

In addition to complete operation of the switches as described inconjunction with FIGS. 8 to 11, t-he power or other drive means may beprogrammed for operation of the gear 91 or 91a through only the initialpart of its movement, whereby to provide for operation of only the shuntand vacuum tube contacts for circuit breaker reclosure service. Shouldthe quick break and reclosure fail to clear the fault, the switch couldthen be fully opened for detailed inspection of the system.

Should it be necessary to inspect or perform maintenance services on theshunt and vacuum tube means of the switch of the invention, the entireswitch structure, i.e., the T component 30, can be lowered away from thetransmission lines to facilitate inspection and maintenance services.For purposes of control of the switch lowering means, it is preferableto provide interlock means (not shown) between the switch opening meansand the lowering means to accommodate operation of the latter onlyfollowing complete switch opening operation of the former.

The foregoing description constitutes the mechanical assembly ofcomponents to form the [presently preferred] embodiment of my switchstructure that was pre- )ferreal at the time I filed my originalapplication for patent on this invention. Since that time, I have workedwith Raymond F. Kupetis and Demetrius Karathanos on improved operatingmechanisms for the Isolating Circuit Breaker, and in this connectioninvite attention to copena'ng applications Ser. No. 24,079, filed Mar.31, 1970, and Ser. No.l9,511, filed Mar. 1 1971. However, whatever thespecific details of the physical or mechanical assembly may be, in orderto attain the ultimate objectives of my present invention, certainelectrical characteristics must be brought into consideration.

lFirst, one purpose of the double [break] disconnection [or] and totalisolation of the interrupters in the open circuit position is to relievethe interrupters, and especially the vacuum gap between their contacts,of all electrical stresses when the switch is open. Similarly, thepurpose of the shunt switches 44 is to relieve the interrupters ofelectrical stress, or at least undue electrical stress, when the switchis closed. Specifically, the shunt assembly 45, 46, 47 (which may forthis reason properly be called the main contact assembly) is selected tocarry, eitheralone or in combination with the interrupters, all of theload current and short time current surges of the circuit withoutimposing electrical stress on the interrupters, Thus, ex-

' 1 1 :ept for the short duration of the final stage of the circuit)reaking function, the interrupters are electrically un- ',tressed andtheir total interrupting capacity is available :'or penformance of thecircuit breaking function.

Second, the operating mechanism is so devised and :onstituted that thetotal circuit breaking function (both )pening of the shunt switches andopening of the inter- ,npter switches) is accomplished very rapidly,e.g., in tive Jr less cycles in the case of a 60 cycle electricalcircuit, whereby further to avoid electrical stress on the interuptersexcept at the moment of circuit breaking. Also, he operating mechanismquickly isolates the interrupters 3y opening the two disconnect contactpairs in approxinately one second following the break, whereby theinterrupters are promptly unstressed and isolated from any return surgesor the like that might tend to restrike an irc between the now openinterrupter contacts. Such iso- .ation also preserves the integrity ofthe vacuum gaps and the interrupter contacts, prevents contactdeterioration :lue to current induced migration, etc.

Third, the interrupters are assembled in multiples in series circuit andare all operated simultaneously thereby (a) to adapt low ratedinterrupters to attainment of the function of carrying the current ofthe high voltage system during the time they alone are in series in thecircuit and (b) simultaneously to impose on the current flow of thesystem a plurality of small but highly effective circuit breaking gapswhereby the voltage is divided over the several gaps to facilitate easeof circuit breaking, or in :he alternative is concentrated at one ormore gaps while the circuit is broken at one or more of the remainder ofhe gaps. Where, as here, there are four essentially identical seriesconnected vacuum tube interrupters subject to fault conditions, avoltage dividing network is asso- :iated with the interrupters to dividethe voltage equally in any conventional manner known in the art.

Fourth, the interrupters assume only a circuit breaking function, noother. In circuit closed position, they are bypassed or shunted andrelieved of electrical stress by the shunt switches; during opening,they are in the circuit only momentarily to make the break; in switchopen position, they are totally isolated from and relieved off theelectrical stress of the circuit; and during closing, the circuit isremade by the shunt contacts to relieve the interrupters of circuitclosing stresses. Thus, the interrupter contacts, like the footballplace-kicker, are kept on the sidelines except for the moment ofperformance of their sole specialty.

In regard to the fourth point, it is further noted that vacuuminterrupters, thus far, employ butt-type contacts and cannot be builtbounce-free. Vacuum is such an efficient interrupting medium that it ispossible to produce multiple interruptions during the contact bounce onclosing. Vacuum contacts thus may erode more rapidly on closing, than oninterrupting. It is for this reason also that the electrical closingduty is removed from the vacuum interrupters and placed on the shuntswitches.

Fifth, both the interrupters and the shunt switches will usually besupplemented by and their load breaking capabilities enhanced bysupplemental insulation. Specifically, the T component 30 of each switchis so constructed that at least the horizontal leg thereof constitutes asealed housing which can be filled with insulating material. In someinstallations, it may prove feasible to employ solid dielectrics such asfoam and the like, and even to fill the housing with filtered oruncontaminated air. Generally, however, and especially where the shuntswitches are mounted in the housing, I prefer to employ high dielectricliquid and gaseous mediums, such as sulphur hexafluoride at two to threeatmospheres pressure, Freon and other like materials.

The presence of this supplemental insulation totally filling theirhousings substantially reduces the open gap requirements of the shuntswitches to facilitate the use of very small switches for high voltages.By virtue of immersion in a high dielectric medium, the shunt contactscan have a short stroke of movement at high speed. They can therefore doa better job of making the circuit than can the interrupter contacts, asabove described, with minimum disturbance to the system and minimumcontact erosion.

In addition, and of particular import, the immersion of the vacuuminterrupters in the high dielectric medium substantially increases theexternal resistance and Hash-over level of the interrupters, whereby thesame may be utilized to the full level of their internal capabilitieswhich traditionally and inherently exceed their external capabilities.

Further, to enhance their capabilities and their reliability, theinterrupters are mounted in back-to-back relation as shown in FIG. 5 toobviate problems consequent upon polarity sensitivity. Also, to insureequal voltage division over the several interrupters, a voltage dividingnetwork is provided.

Finally, I utilize the interrupters at levels far exceeding theirpurported capabilities, and I am able to do so with complete safety andreliability because of the foregoing factors; i.e., maintaining theinterrupters in electrically unstressed condition to maintain their peakinternal capabilities, supplementing their external capabilities tobring them'to an increased level approaching their peak internalcapabilities, exposing them to the electrical stress of a circuit breakin the short duration of a few cycles, and dividing or spreading thecircuit breaking stress over a plurality of vacuum gaps.

Referring to FIG. 12, and taking a 15 kv. vacuum tube interrupter switchas an example, the present invention provides for development,interpretation and gainful employment of the curve A, which is acomposite of the withstand Values inherent in the tube. Specifically itis a composite of (1) the dielectric recovery of the vacuum gapfollowing an interruption-the slope of the curve, which mustfundamentally exceed the system transient recovery characteristicplotted at B, and (2) the maximum voltage one minute 60 cycle withstandcapability of the switch-the peak value of the curve.

In obtaining the peak value of curve A, I observe that a vacuum tubeinterrupter rated at 15 kv. continuous service is required to have a 50kv., one minute, 60 cycle, RMS voltage withstand capability. This RMS oreffective value means that the maximum voltage withstand is at least70.7 kv., i.e., 50 times the square root of 2. Therefore, theinterrupter must provide a basic 70.7 kv. transient recovery reference,indicated by the horizontal part of curve A, upon which I am able torely because of the above explained characteristics of my switch.

As for the slope of curve A, I observe that following an arcing event,the dielectric strength of the vacuum gap starts at a value of the arcvoltage at the instant of current zero and grows to a peak value. Therate at which the dielectric strength grows depends on the magnitude,the character and the distribution of the energy at the instant ofcurrent zero and its rate of decay from the vacuum gap system followingthe current zero. Every vacuum tube switch is designed to transport acertain maximum magnitude of energy across the vacuum gap during anarcing event (maximum current) and to cause a decay of the residualenergy at least at a defined minimum rate to assure that the currentwill not resume as the system applies a transient recovery voltageacross the vacuum gap.

In the example of FIG. 12, the 15 kv. module is designed to withstand atransient voltage having its rst peak of 29.2 kv. at 32.7 micro-seconds,curve B. Therefore, the minimum dielectric recovery strength of thismodule must be greater than curve B from the time of current zero to32.7 micro-seconds following current zero.

The ultimate dielectric strength of the vacuum gap and all parts inparallel `with the vacuum gap of the switch must be equal, at least, to70.7 kv.-the one minute withstand value.

There are no defined mechanisms that cause an abrupt change in theinitial rate of dielectric recovery for gaps of the dimensions of theaverage vacuum tube of this modules rating.

Therefore with a defined ultimate value (70.7 kv.) and a defined initialrate (greater than 29.2 kv. in 32.7 microseconds) an exponentialcurve/can be drawn and defined as the minimum dielectric recovery curvefor the particular -vacuum switch-curve A.

To apply a vacuum tube as a module of a high voltage system, thetransient recovery characteristic of the system is divided by the numberof modules to be employed. If the divided system transient is at alltimes less than the dielectric recovery ability of the individual moduleand the system voltage is uniformly dividedracross the modules, thenthis combination of modules is capable of [interrupting] stopping theflow of current of the high voltage system.

The transient recovery voltage is super-imposed on the 60 cycle systemrecovery voltage. Therefore, each module must be capable of withstandingits portion of the continuous 60 cycle system voltage for the timebetween circuit interruption and isolation of the interrupter from thesystem. This is a time duration of cycles to tens of cycles andtherefore may be equal to or less than the 60 cycle one minute withstandvalue of the module.

Applying these concepts to the design of a circuit breaker for 138 kv.,we find that for load and fault switching the maximum phase voltage isequal to 145 kv. (the phase to phase potential) divided by the squareroot of three (the standard constant) or 83.6 kv. RMS. This valuedivided by the individual modules one minute RMS withstand of 50 kv.yields 1.67, whereby two 1S kv. vacuum tube modules would satisfy thenormal 60 cycle voltage stress of the system.

However, the maximum 60 cycle stress of a breaker in line positionoccurs when that breaker switches an openended line, such stress being2.4 times the normal stress or 200 kv. RMS in a 138 kv. system. Towithstand this stress (200 divided by 50) requires four of the modules.

Dividing the standard values of system recovery voltage transients bythe number of modules thus tentatively selected and plotting theresults, curve C of FIG. 12, reveals that the transient stresses are atall times no greater than the minimum dielectric recovery strength ofthe individual module, curve A.

Therefore, four 15 kv. vacuum tube modules fully satisfy the most severe60 cycle voltage stress and the complete transient recovery stress of13S kv. system when applied according to this disclosure.

If a 138 kv. circuit [breaker] switcher (combination disconnect andinterrupter) were built using 15 kv. modules without considering theteachings of this disclosure, it would require 10 modules, or 21/2 timesthe number provided by this invention.

'Ihus, in contrast to the prior art, the present invention cancontemplate a practical 138 kv. 1600 Amp Isolating Circuit Breakerhaving the following characteristics:

BREAKER RATING 138 kv. Nominal Voltage 145 kv. Voltage 335 kv. 60 cycle1 min. withstand dry 275 kv. 60 cycle 10 sec. withstand wet 650 kv. BIL11/2 40 wave 1600 amps continuous 70 ka. momentary (10 cycle) 40 ka.short time (3 secs.)

12 ka. fault switching to 160 amps magnetizing current 70 amps capacitorcurrent 70 ka. making current Interrupting time-milliseconds Isolatingtimesecond Closing ti-me-second(s) Reclosure withoutisolation-milliseconds Reclosure with isolationsecond(s) as shown in thedrawings and mounted on the rotatable` stack 31. The isolating functionis accomplished by rotating the stack to provide a visibly open switchdimensioned to withstand all voltage stress of the system. Thedisconnect contacts will interrupt any residual current of voltagedistribution resistor-capacitor networks.

The operating mechanism 0f the switch provides the opening and closingoperations previously described, and can be sequenced to open only theshunt or main contacts and the vacuum switch contacts for reclosureservice. The isolating portion of the switch will be operated whenfaults are not cleared by single reclosure and/or where isolation isrequired or desired. The operating mechanism should preferably drive allcontacts to closed position and in doing so should preferably load anenergy storage device for high speed opening of the shunt and vacuumcontacts. Only the disconnect would be opened by the operating mechanismper se.

In the light of the foregoing, the present invention visualizes a familyof Isolating Circuit Breakers applicable to practically all commonlyused transmission and distribution voltages.

Effective circuit breaker operation, especially at the higher levels, ispredicated upon immersion of currently available vacuum tubes in a highdielectric medium, bypassing the tubes with adequately rated shunt ormain Contact means in the closed circuit position, and isolation of thetubes from the system in open circuit position. At the lower voltages,the shunt may be external of the tube housing, but at high voltages theshunt is preferably within the housing and immersed in the dielectric.

In this way the objects and advantages of the invention are attained ina convenient, economical, practical, and safe and reliable manner.

While I have shown and described what I regard to be the preferredembodiment of rny invention, it will be appreciated that changes,rearrangements, variations and modifications may be made therein withoutdeparting from the scope of the invention, as dened by the appendeclaims.

I claim:

1. A circuit breaker for breaking a circuit operating at a givencontinuous voltage and having a known maximum voltage stress comprising,in combination, interrupter switch means for breaking the circuit havinga given continuous service voltage rating less thank the continuousvoltage of the circuit and transient voltage capabilities at least equalto the maximum voltage stress of the circuit, and means for [isolating]relieving said interrupter switch means from circuit stress except atthe moment of circuit breaking operation of said interrupter switchmeans, so that the interrupter switch means [can perform circuitbreaking operations] operates at the level of the transient capabilitiesthereof rather than the continuous service ratings thereof to performcircuit breaking operations.

2. A circuit breaker as set forth in claim 1, said stress relievingmeans including by-pass switch means in parallel circuit with saidinterrupter switch means of a current carrying capacity to maintain saidinterrupter switch means essentially in electrically unstressedcondition in the closed circuit position, disconnect switch means forcompletely isolating the entirety of said interrupter switch means fromthe circuit in the open circuit position, and Jperating means for firstopening said by-pass switch means, second opening said interrupterswitch means and :hen opening said disconnect switch means so that saidinterrupter switch means is subject to electrical stress substantiallysolely at the moment of circuit interruption, and for first closing saiddisconnect switch means, second closing said by-pass switch means andthen closing said interrupter switch means so that said interrupterswitch means is not exposed to circuit closing stresses.

[3. A circuit breaker as set forth in claim 2, wherein said operatingmeans includes means for irst closing said disconnect switch means,second closing said by-pass switch means and then closing saidinterrupter switch means so that said interrupter switch means is notexposed to circuit closing stresses] 4. A circuit breaker [for breakinga circuit operating at a given voltage and a given continuous currentload] as set forth in claim 1, said interrupter switch means cornprisinga plurality of interrupters connected in series with one another [andsaid disconnect switch meansl, said interrupters each having a standardcontinuous voltage rating, a one minute RMS voltage withstand rating anda continuous current rating, with the continuous current ratingsubstantially equal to the continuous current load of the circuit; theinterrupters being of such number and voltage ratings that the 60 cyclerecovery voltage and the transient recovery voltage of each of theinterrupters is not substantially greater than approximately its voltagewithstand rating but such that the per phase voltage of the circuitdivided by the number of interrupters equals a voltage in excess of thecontinuous voltage rating of each interrupter.

5. A circuit breaker as set forth in claim [4] 1, said interrupterswitch means comprising a plurality of interrupters connected in serieswith one another, said interrupters being mounted electrically in backto back relation with the movable contact of one interrupter juxtaposedto the movable contact of the interrupter next adjacent one end thereofand with the stationary contact of said one interrupter juxtaposed tothe stationary contact of the interrupter next adjacent the opposite endthereof, whereby to mitigate polarity sensitivity of said interrupters.

`6. A circuit breaker `as set forth in claim [4] 5, including a voltagedividing network in combination with said interrupters.

7. A circuit breaker as set forth in claim [4] 5, said stress relievingmeans including by-pass switch means in parallel circuit with saidinterrupters for maintaining said interr'upters electrically unstressedin circuit closed position, disconnect switch means for completelyisolating all of said interrupters from the circuit in the open circuitposition, and operating means for lirst opening said bypass switchmeans, second opening said interrupters and then opening said disconnectswitch means, and for first closing said disconnect switch means, secondclosing said by-pass switch means and then closing said interrupters.

8. A circuit breaker as set forth in claim 7, said interrupterscomprising vacuum tube interrupters, a housing enclosing said vacuumtubes and said by-pass switch means, and a dielectric medium fillingsaid housing and immersing said vacuum tubes and said by-pass switchmeans.

9. A circuit breaker for breaking a circuit operating at a givencontinuous voltage and a given continuous current load and having aknown maximum voltage stress comprising, in combination, interrupterswitch means having a continuous current rating substantially equal tothe continuous current load of the circuit and having a given continuousservice voltage rating less than the continuous voltage of the circuitand transient voltage capabilities at least equal to the maximum voltagestress of the circuit, means for maintaining said interrupter switchmeans essentially in electrically unstressed condition in the closedcircuit position, disconnect switch means in series circuit with Saidinterrupter switch means for completely isolating the entirety of saidinterrupter switch means from the circuit in open circuit position, andoperating means for first imposing the circuit load on said interrupterswitch means, then openingsaid interrupter switch means and thereafteropening said disconnect switch means [so that] for completely removingthe entirety of said interrupter switch means [is completely removed]from the circuit immediately following circuit breaking operation,[whereby] so that said interrupter switch means [can be of a continuousvoltage rating less than the continuous voltage of the circuit 'and canperform circuit breaking functions] operates at the level of thetransient capabilities thereof rather than the continuous serviceratings thereof to perform circuit breaking operations.

10. A circuit breaker as set forth in claim `9, including a housingenclosing said interrupter switch means, and a high dielectric mediumfilling said housing and immersing said interrupter switch means, saidhousing comprising essentially an insulated member having contacts atits ends connected in series circuit with said interrupter switch means,said housing being movable and comprising said disconnect switch means.

11. A circuit breaker for breaking a circuit operating at a givencontinuous voltage and a given continuous current load and having aknown maximum voltage stress comprising, in combination, vacuum tubeinterrupter switch means having a continuous current ratingsubstantially equal to the continuous current load of the circuit andhaving a continuous service voltage rating less than the continuousvoltage of the circuit and transient voltage capabilities at least equalto the maximum voltage stress of the circuit, bypass switch means inparallel circuit with said interrupter switch means of a currentcarrying capacity to maintain said interrupter switch means essentiallyin electrically unstressed condition in the closed circuit position,disconnect switch means in series circuit with said interrupter andby-pass switch means for cornpletely isolating the entirety of saidinterrupter switch means from the circuit in open circuit position tomaintain the entirety of said interrupter switch means in electricallyunstressed condition in the open circuit position, and operating meansfor first opening said -by-pass switch means, second opening saidinterrupter switch means and then openingl said disconnect switch means,and for first closing said disconnect switch means, second closing saidby-pass switch means and then closing said interrupter switch means soas to relieve the latter of circuit closing stresses, whereby saidinterrupter switch means [can] performs circuit breaking operations atthe level ofthe transient capabilities thereof rather than thecontinuous service ratings thereof.

'12. A circuit breaker as set forth in claim 11, including a housingenclosing both said interrupter switch means and said `by-pass switchmeans and an insulating medium iilling said housing and immersing bothof said switch means.

13. A circuit breaker as set forth in claim 12, said disconnect switchmeans comprising a pair of stationary disconnect switch contacts mountedadjacent the opposite ends of said housing and a pair of contacts on theends of said housing, said housing comprising essentially an insulatedmember having its contacts connected in series circuit with sadinterrupter switch means and said by-pass switch means, said housingbeing movable to move its contacts into and out of engagement with saidstationary contacts whereby said housing comprises disconnect switchmeans of the double break type.

14. A circuit breaker comprising a spaced pair of stationary contacts,[an insulating] a housing normally extending between said pair ofstationary contacts and having contacts at its ends for engagement withsaid stationary contacts, said housing comprising a plurality ofinterconnected insulating segments, an interrupter switch [means]mounted in its entirety in each said housing segment and each havingseparable contacts, the

interrupter switches in adjacent segments being mounted in alternatedirections so that the movable contact of each interrupter switch isjuxtaposed to the movable contact of a next adjacent interrupter switch,said contacts of said interrupter switches being connected in seriescircuit with one another and the contacts at the ends of said housing,and operating means for rst opening said interrupter switches [means] toEbreak the c-ircuit and then moving said housing and its contacts awayfrom said stationary contacts to completely isolate the entirety of saidinterrupter switches [means] from said stationary contacts, [whereby toadapt said interrupter switch means to circuit breaking operations atthe transient capabilities thereof rather than the continuous servicerating thereof] said operating means including means interposed betweenthe adjacent ends of each pair of housing segments at which the movablecontacts of the interrupters are juxtaposed jor simultaneously openingeach juxtaposed pair of movable interrupter contacts.

15. A circuit breaker as set forth in claim 14, including shunt switchmeans in parallel circuit with said interrupter switch means and seriescircuit with said housing contacts of a current carrying capacityadequate to maintain said interrupter switch means in electricallyunstressed condition in the closed circuit position, 'said operatingmeans upon switch opening movement rst opening said shunt switch means,second opening said interrupter switch means to break the circuit andthen moving said' housing to isolate said interrupter 'switch means fromthe circuit and maintain the same in electrically unstressed conditionin the open circuit position, said operating means upon switch closingmovement first moving said housing to engage its contacts with -saidstationary contacts, second closing said shunt switch means to close thecircuit, and then closing said interrupter switch means to relieve thelatter of circuit closing stresses.

16. A circuit breaker as set forth in claim 15, said shunt switch meansbeing mounted in said housing, said housing being filled with a highdielectric medium in which said interrupter switch means and said shuntswitch means are immersed.

17. A circuit breager [as set forth in claim 14, including] comprising aspaced pair of stationary contacts, an insulating housing normallyextending between said pair of stationary contacts and having contactsat its ends for engagement with said stationary contacts, interrupterswitch means mounted in its entirety in said housing and havingseparable contacts connected in series circuit with the contacts at theends oj said housing, operating means for first opening said interrupterswitch means to break the circuit and then moving said housing and itscontacts away from said stationary contacts to completely isolate theentirety of said interrupter switch means from said stationary contacts,a stationary frame mounting said stationary contacts, and a movable'frame mounted on and guided by said stationary frame, said housingbeing mounted on said movable frame, said operating means includingmeans operable subsequent to switch opening movement of said housing formoving said movable frame to remove said housing physically from theenvironment of said stationary contacts to accommodate safe servicing ofsaid' housing and said interrupter switch means.

18. A circuit breaker a's set forth in claim 17, said housing comprisinga T-shaped component having a horizontal leg containing said interrupterswitch means and a vertical leg rotatably mounted on said movable frame,said movable frame being vertically reciprocable on said stationaryframe, said operating means rotating said component into and out ofengagement with said stationary contacts and vertically reciprocating'said movable frame when saicl component is out of engagement with saidstationary contacts to move said component into and out of theenvironment of said stationary contacts.

19. A circuit breaker comprising a pair of spaced stationary contacts, ahousing normally extending between said 'stationary contacts and havingcontacts at its ends normally engaging said stationary contacts, saidhousing [in essence being insulating between its said contacts, aplurality of] comprising a plurality of interconnected insulatinghousing segments, an interrupter switch[es] mounted in [their entiretyin] each said housing [and] segment, said interrupter switches beingconnected in series circuit with one another and said housing contactsto establish an electrical circuit between said stationary contacts, theinterrupter switches in adjacent housing segments being mounted inalternate directions so that the movable contact of each interrupterswitch is juxtaposed to the movable contact of a next adjacentinterrupter switch, operating means between the adjacent ends of eachpair of housing segments at which the movable contacts of a pair ofinterrupter switches are juxtaposed including spring biased snap actionoperating means [in said housing] for simultaneously opening [all of]said interrupter switches, and an operating mechanism connected to 'saidhousing and said operating means operable upon switch opening movementfor initially effecting operation of said operating means to open saidinterrupter switches at high speed to break said circuit and forsubsequently moving said' housing and its contacts away from saidstationary contacts to isolate said housing and the entirety of saidinterrupter switches from said stationary contacts, said operatingmechanism being operable upon switch closing movement for rst vmovingsaid housing and its contacts back into engagement with said stationarycontacts and subsequently effecting operation of said operating means toclose said interrupter switches.

20. A circuit breaker as set forth in claim 19, including shunt switchmeans in parallel cricuit with said interrupter 'switches andI seriescircuit with said housing contacts, said operating mechanism includingmeans for opening said shunt switch means prior to opening of saidinterrupter switches and for closing said shunt switch means subsequentto movement of said housing back into engagement with said stationarycontacts but prior to reclosing of said interrupter switches.

21. A circuit breaker as set forth in claim 20, said operating mechanismincluding means for opening and closing said shunt 'switch means andsaid interrupter switches independently of movement of said housing forcircuit breaker reclosure service.

22. A circuit breaker as set forth in claim 19, including a shuntswitch[es] in each of said housing segments [of the same number as saidinterrupter switchesl, said shunt switches a'lso being mounted inalternate directions and connected in lseries circuit with one anotherand said housing contacts and in parallel circuit with said interrupterswitches; said operating means including first drive means connected to[said] the respective pair of shunt switches for operating the samesimultaneously and second drive means connected to [said] the respectivepair of interrupter switches for operating the latter simultaneously,said' second drive means having a lost mo-tion connection with said r'stdrive means in both the switch opening and the switch closing directionswhereby said shunt switches are opened prior to the opening of saidinterrupter switches and are closed prior to the closing of saidinterrupter switches; said second drive means including biasing meansfor effecting high 'speed opening of said interrupter switches.

23. A process of breaking a high voltage, high current electricalcircuit by interrupter means and disconnect means, comprising the stepsof inserting in series in each phase of the circuit a plurality ofinterrupters having transient voltage capabilities the composite ofwhich is approximately equal to and at least as great as the maximumvoltage stress of the phase; inserting a pair of disconnect means inseries in the circuit to opposite sides of said interrupters;maintaining said interrupters essentially in electrically unstressedcondition when the circuit is closed; imposing the full circuit load onthe interrupters when it is desired to break the circuit and thereuponsubstantially simultaneously operating all of said interrupters to opencircuit position; and substantially im mediately thereafter completelyisolating the entirety of said=interrupters from the circuit byoperating said disconnect means to open circuit position; whereby saidinterrupters [may be] are operated at the level of their V transientcapabilities rather than their continuous voltage ratings to performcircuit breaking operations. I

24. A process as set forth in claim 23, including the step of enhancingthe capacity of said interrupters by' 26. A process as set forth inclaim 25, including the step of closing the circuit by irst closing saiddisconnect means, second closing said shunt conductors and finallyclosing said interrupters.

27. A circuit breaker comprising, in combination, interrupter switchesfor breaking the circuit and means for [completely isolating] relievingthe entirety of said interrupter switches from voltage stress -except atsubstantially the moment of circuit breaking operation of saidinterrupter switches, [so that] said means completely isolating theentirety of the interrupter switches [have no] from the circuit and thusfrom electrical stress [thereon] in the 'open circuit position [and canperform], said interrupter switches having composite transient voltagecapabilities atleast as great as and approximately equal to the maximjumvoltage stress of the circuit for performing circuit breaking operationsat the level of the transient capabilities thereof rather than thecontinuous service ratings thereof.

28. A circuit breaker as set forth in claim 27, wherein said [isolating]stress relieving means [comprises] includes disconnect switches iriseries with said interrupter switches to opposite sides-thereof forcompletely isolating the entirety of said interrupter switches from thecircuit in the open circuit position.

29. A- process of breaking a high voltage, high current electricalcircuit by interrupter means, comprising the steps of inserting inseries in the circuit.interrupter means having a given continuousservice voltage rating the composite of which is less than thecontinuous voltage of the circuit and having transient voltagecapabilities the composite of which is at leastk equal to the maximumvoltage stress of the circuit, relieving said interrupter means fromcircuit stress except at the moment when the circuit is to be broken,imposing the full circuit load on said interrupter means only when it isdesired to break the circuit and thereupon substantially simultaneouslyoperating said interrupter means to open circuit position andimmediately thereafter completely isolating the entirety of saidinterrupter means from the circuit, so that said interrupter meansarefpperated at the. level of the transient voltage capabilities thereofrather than the continuous voltage rating thereof to perform circuitbreaking operations.

30. A process as set forth in claim 29, including the steps ofmaintaining the interrupter means in unstressed condition when thecircuit is closed by normally shunting said interrupter means withconductors having adequate current carrying capacity to maintain saidinterrupter means electrically unstressed, and isolating the interruplermeans from the circuit when in open circuit p0- sition by opening a pairof disconnect means connected in series circuit with said interruptermeans to opposite sides thereof.

31. A process as set forth in claim 30, including the step of closingthe circuit by first closing said disconnect means, second closing saidshunt conductors and jnally closing said interrupter means.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

UNITED STATES PATENTS 2do-145, 14s D

